Vacuum dehydration of beets



'the chamber.

Patented June 25, 1946 VACUUM DEHYDRATION OF BEETS Robert M. Schafi'ner, Chicago, 11L, assignor to The Guardite Corporation, a corporation of Illinois No Drawing.

Application May 31, 1944,

Serial No. 538,199

2 Claims. (Cl. 99-204) This invention relates to the vacuum dehydration or beets. I

The customary dehydrationof beets results in the loss of the characteristic dark red color thereof. It has been found that the use or vacuum dehydration processes under proper conditions results in the retention of the color and flavor of the original beet even after cooking.

The beets are washed free of earth and may then be peeled by abrasion or chemical means or may be pressure cooked with the skin on and then peeled by machine or by hand. If the beets are first peeled they are then diced or sliced to athickness of not more than inch and loaded on screen-bottomed drying trays. Loadings of 1 1b. to 1.8 lbs. per square foot or screen area are employed. The beets are then transferred to a cooker which is evacuated to remove the air after whichlsteam is introduced to bring the temperature of the beets from 200 to 250 F. It has been found that bringing the temperature rapidly in the chamber to 240 F. and maintaining it at that point for minutes is satisfactory. The beets are then quickly cooled If the beets have not been peeled they are loaded in any suitable manner within the cooker and cooked for 10 to 20 minutes at temperatures of approximately 240 F. The cooked beets are then cooled by evacuating the chamber or by cold running water. They are then peeled by hand or by machine and sliced or diced. They may then be loaded on dryin trays at the previously indicated loading limits of 1 lb. to 1.8 lbs. per square foot. The beets are then given a second cooking after the chamber has been evacuated to remove the air. This may be at a temperature of 200- 250 F., but, in view of the previous cooking, the time required is not great. For example, a satisfactory product was produced by cooking for 10 minutes at 206 F. It is desired to cook the product to a point where it is Just short or losing its texture and becoming mushy, because even though this results in a wetter initial product, the final product has a lower moisture content, as described in my co-pending application, Serial No. 638,091, filed May 30, 1944. After cooking, the beets are cooled by evacuating the chamber to about inch absolute to produce a temperature above 60 F.

by evacuating The beets produced by either of the foregoing processes are then ready for drying. They are preferably passed to a dryer without contact with air and are dried therein at a low pressure, preferably below 100 mm. of mercury.

The preferred dryer is described in Heineman application, Serial No. 520,773, filed February 2, 1944, and Baer application, Serial No. 524,177, filed February '28, 1944. In this type of dryer the pressure is maintained consta t throughout an elongated drying zone, down .1011 the material to be dried passes. The material is maintained in trays which are surrounded at all times by heating coils which are heated by internal steam. superheated steam is also introduced to the apparatus at the beginning and end thereof and withdrawn centrally of the device. The average distance from the coils to the material to be dried is about 3 inches. The normal pressure is approximately 57 mm.

Under these conditions, the radiant heat surfaces were maintaine at the varying tempera tures for the following successive times:

Minutes of exposure Radiant suriace temperature The product so treated was an open market beet of the Detroit Dark Red type, processed approximately 118 ho :s after harvest. The ma, terial had a moisture content of 89% after blanching, and a final moisture content of 3.9% after drying. The color was good, and the flavor of the product after rehydration was good, as wasits texture. The dehydration. ratio, which is the original weight divided by the dehydrated weight, was 8.76. The rehydraticn ratio, which is the weight of the dried product after 30 minutes of boiling in water divided by the dehydrated weight, was 5.73. The reconstitution percentage, which is the rehydration ratio divided by the dehydration ratio, was, therefore, 65.4. The prodloaded on trays at 1.40 lbs. per square inch, and

again blanched at 202 F. for 10 minutes.

accepts The following table shows other results:

"var! ty 333,? P rt a WW 1 1 ime k B BM e e co 1 rs or 53%; Detroit Early W0 1' Red Ball Processed, hrs. after harvest I l 46 113 121 137 234 234 Original moisture, percent (after retort bleach)..-" 88. B 80. 5 '86. 7 84. 7 v 80. 7 89. 0 89. 6 89. 6

Final moisture, percent u a1 a. a an 2.7 an 3.1 4,2

Flavor of rehyd. product Good Good Good Good Good Good Good Good Texture of rehyd. product.--" Good Good Good Good Good Good Good Good Dehyd. ratio (orig. wt.ldehyd.wt.) .L 8.8 8.00 I 7.56 -7. 2) 7.21 8.1!) 8. 51 9.45

Rehyd. ratio-30 min. boil (rehyd. wtJdehyd. wt.). 5. 34 47 4. 53 4. 82 4. 59 4.40 4.86 8.86

' Reconstitution, percent '(rahyd. r/dchyd. 12).. 63.8 66.0 59.8 60.0 63.7 65.1 61.2 41.0

Pretreat retort (also wash, peeled, 9i" dice):

Min. 20 20 20 Z) Z) Z) Temp 240 240 240 240 240 240 Loading, lbs/sq. it 1.40 1.41 1.41 1.41 1. 41 1. n 54 dice 5 slice Machine blanch: i

Min 1O 10 10 10 10 'lem m an 207 '21) 211 206 Drying cycle: I P M P M P M P M P -M P M P-p. s i. steam coil 20 40 20 40 m 40 20 40 20 40 M-rnimites 10 40 10 40 10 40 10 40 10 40 10 40 5 190 5 130 5 130 5 130 6 130 5 130 2 a0 2 90 2 90 2 90 2 90 2 90 an 300 300' coo not act Finishing temp F 171-177 183489 180-196 164F167 205 203 179- 1 Hrs. alter nurchasc.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom. l I

What I claim as new, and desire to secure by Letters Patent, is:

1. The method of processing beets which com- .prises loading whole beets into a cooker and temperature of 200-250 F. in the absence or air for approximately ten minutes, cooling the beets by evacuating the chamber, transferring them to a dryer without contact with air, and drying under reduced pressure in an atmosphere of 511- 

